1. Field of the Invention
The present invention relates generally to the field of medical systems, and more specifically to managing power for wireless devices.
2. Description of the Related Art
Current medical system product offerings typically transmit signals over a fixed wire or cable to connect removable or non-fixed subsystems and devices. Traditionally, these non-fixed wired subsystems and devices employ the same fixed wire connection to receive a constant reliable source of power. Examples of removable or non-fixed wired devices include monitors or monitoring equipment, test equipment, remote control devices, footpedals, and so forth.
The rapid advancement and proliferation of short-range radio technology now affords medical system product designers and manufacturers the ability to create and deploy non-fixed subsystems and devices without need for a conventional fixed physical communication cable. For example, non-fixed devices meeting or complying with the Institute of Electrical and Electronics Engineers (IEEE) 802.11g, IrDA (infrared data), and Ericsson Bluetooth™ specifications provide short-range radio technology to enable for wireless communications. These technologies enable the wireless transmission of signals over short distances between telephones, computers and other electronic devices. Bluetooth™ enabled devices are capable of an approximate 10-meter transmission range at data rates up to 720 kilobits/sec and provide better security features than devices implementing IEEE 802.11g communications.
However, the Bluetooth™ and IEEE 802.11g specifications only address the transmitting and receiving of communication and control signals. Non-fixed wireless medical subsystems and devices are typically without a fixed continuous reliable power source (i.e. wired alternating or direct current) and rely on internal batteries for operation when active. Due to the critical health support requirements for medical equipment and the potential catastrophic consequences of a power failure in such equipment, effective deployment of medical systems incorporating wireless devices require a highly reliable battery power management scheme to ensure a constant source of power to fielded non-fixed wireless subsystems and devices.
These active wireless medical devices, when used under normal operation, are exposed to numerous electrical safety and reliability issues. An example of safety issues include the wireless device and associated battery-charging mechanism (e.g. charging cradle or alternating current transformer) coming in contact with various caustic and corrosive chemicals and fluids in the operating theater. An example of reliability issues includes ensuring a battery health and status indication is available at all times to the user, such as a surgeon, thus ensuring consistent successful non-fixed wireless device operation.
Moreover, wireless medical subsystems and devices that use batteries as their power source are typically only available for a recharging cycle at the end of the surgery day when the device is not in operational use. At the end of the surgical day, medical systems and non-fixed wireless devices are typically moved and stored to the side of the operating room, frequently away from a source of electrical power. This poses a particular challenge for power management schemes, since operating room medical systems are unplugged from AC line power for storage at the end of the surgery day and power is not available for recharging the wireless subsystems and devices. Thus over a typical 24 hour operating day, the wireless device is in operation or available to the surgeon/user for a large part of the day and plugged into a base or recharger having no source of power. Reliable wireless device power management schemes in this environment must not only provide a reliable source of power but must also provide a mechanism for monitoring and reporting battery condition for wireless subsystems and devices, when an alternating current or direct current source is not available.
Thus it would be advantageous to offer an architecture and design that provides wireless battery operated subsystems and devices a reliable and highly available power management scheme to ensure safe and continuous peripheral product operation in an environment where the wireless device and base unit each have no source of power for extended periods of time.